$font-song:Georgia, "Nimbus Roman No9 L", "Songti SC", "Noto Serif CJK SC", "Source Han Serif SC", "Source Han Serif CN", STSong, "AR PL New Sung", "AR PL SungtiL GB", NSimSun, SimSun, "TW\-Sung", "WenQuanYi Bitmap Song", "AR PL UMing CN", "AR PL UMing HK", "AR PL UMing TW", "AR PL UMing TW MBE", PMingLiU, MingLiU, serif;
$font-kai: Baskerville, Georgia, "Liberation Serif", "Kaiti SC", STKaiti, "AR PL UKai CN", "AR PL UKai HK", "AR PL UKai TW", "AR PL UKai TW MBE", "AR PL KaitiM GB", KaiTi, KaiTi_GB2312, DFKai-SB, "TW\-Kai", serif;
$font-hei:-apple-system, "Noto Sans", "Helvetica Neue", Helvetica, "Nimbus Sans L", Arial, "Liberation Sans", "PingFang SC", "Hiragino Sans GB", "Noto Sans CJK SC", "Source Han Sans SC", "Source Han Sans CN", "Microsoft YaHei", "Wenquanyi Micro Hei", "WenQuanYi Zen Hei", "ST Heiti", SimHei, "WenQuanYi Zen Hei Sharp", sans-serif;
$color-highelight:rgb(15, 81, 15);
// 占位符placeholder
// 于引用父选择器并为其添加伪元素样式。这个用法是正确的，但前提是它必须位于一个有效的选择器内部。
%clearFix{
    &::after{
        content: "";
        display: block;
        clear: both;
      }
}
%out{
    box-shadow: 0 0 5px rgba(0,0,0, 0.25);
}
%in{
    box-shadow: inset 0px -5px 5px -5px rgba($color: #000000, $alpha: 0.5),
                inset 0px 5px 5px -5px rgba($color: #000000, $alpha: 0.5)
}